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WernerNYK
02-10-2002, 09:11 PM
Heh....it's great to see all the amazing gripper designs out there....some teams put so much work and thought into designing something that will work well....although we are a rookie team, it seems that many teams forget the basic rule of thumb: K.I.S.S. (Keep It Simple Stupid)

Our gripper design is extremely simple...at first glance you may not even realize that it's a gripper or how it would work. I dont have any completed pictures right now, but I will take some pictures tomorrow to post up here....it is an almost guaranteed grip every single time regardless of our position/angle to the goal...i've seen so many teams over-engineer their gripper, and they need to be lined up correctly in order to grab the goal, heh....

well, I'll post up some pics tomorrow afternoon....and you'll also get to see our "mean wheels," shined aluminum sides (not to be mistaken for mirrors :p ), and bumpers (are other teams even using bumpers??....I havent seen any in any pictures yet :confused: )

-Chris
West Islip Robotechs
Team #871

WernerNYK
02-10-2002, 09:21 PM
well, here is a picture from about a week ago....MUCH has changed since then....our bot was half-dissasembled at this point....:D

Wetzel
02-11-2002, 01:47 AM
No bumpers cause we are still (at last I knew) 25 lbs overweight.:eek:
And you are right, I don't see how the hook works. Unless there is part of the mechanism missing...

WernerNYK
02-11-2002, 06:21 PM
OK well, here is a picture of our gripper as of today...it was mounted earlier, but we had to remove it to let some epoxy set....But just picture this at the end of the cylinders in the above picture... How much simpler could you get?? And it's guaranteed to work ;)

http://www.chiefdelphi.com/pics/bin/1013472648Dsc0011.jpg

Brett W
02-11-2002, 06:32 PM
i can't believe our team didn't think of that that is soo simple i had thought that we had the most simple deign possible but i guess not oh well. Nice job anyways and good thinking

Matt Ryan
02-11-2002, 08:13 PM
Originally posted by WernerNYK
OK well, here is a picture of our gripper as of today...it was mounted earlier, but we had to remove it to let some epoxy set....But just picture this at the end of the cylinders in the above picture... How much simpler could you get?? And it's guaranteed to work ;)

http://www.chiefdelphi.com/pics/bin/1013472648Dsc0011.jpg

NOTHING is guaranteed to work :D. In the pits, it works fine, but in the two minutes it takes to get to the playing field, it decides not to work :p. It happens.

VThokieME04
02-12-2002, 01:13 AM
This is my fourth year in the competition, and if there is one thing i've learned is that there is never a simple solution to such a complex problem. There are many approaches to solving the problem of latching on to the goal and doing it well is a whole other subject. Many teams last year successful manufactured simple gripping devices and had a mixture of both success and failure.

After last years competition, my team decided to invest in a little down-time construction of a test platform of a gripping device that would latch on to something like a small vertical pole. We tried your design, almost exactly. And we realized one thing, simple isn't always the best. The geometry of the design and the nature of the game does not allow for an easy time in grabbing on to the goals. The success of the design was so variable that we decided against anything close to it this year. I encourage your team to do some bizzare testing. Try to latch on to the goal while a student is moving it around. Try to latch onto the goal when your driver is 48 feet away. You might discover that an almost religious pursuit of the K.I.S.S principle leaves your team with a very simple robot that can't compete.

WernerNYK
02-14-2002, 07:52 PM
Ok, well we've been done for a few days now.....just been tweaking things a little so I havent been able to get a completed picture until now......Keep in mind that this is a rookie team, without a machine shop (all we have are a few old lathes and drill presses), and without any corporate engineering sponsors :D

....and look at the shiny sides :cool:

http://www.chiefdelphi.com/pics/bin/1013737270P213002.jpg

MrB
02-19-2002, 12:06 PM
well hell, we did it from 48 ft son, and i got it down. wait until gametime, hahahahahah- DJSKRABL22 (hahahahahahahahaha)

Matt Reiland
02-19-2002, 12:27 PM
Here is our 'not simple' goal grabbing design
K.I.S.S. didn't work for us

The linkage collapses to go into a goal (the point allows it to find the area between the goals if we happen to hit a post) then springs back to form the diamond inside of the bars, at this point it is latched in. To release the pressure is now on the bars facing the robot and a latch restricts the outward facing bars from compressing outward. A servo pulls the finger latch out of the way and allows us to release from the goal. It is incedibly strong as you can see from the picture( 3 parallel pieces of Bosch rail capped by six inch x 1/4" aluminum and it telescopes in and out). One of our strategies is that of a dog playing tug of war that almost rips your arm off. We latch on then start driving sideways back and forth (4 wheel crab steer 12 ft/sec) to rotate the goals in your gripper. Non-robust grippers will be bent almost immediately.

WernerNYK
02-19-2002, 03:33 PM
Non-robust grippers will be bent almost immediately.


.......real nice...:confused:

Matt Reiland
02-19-2002, 04:47 PM
You can always let go ;)

Seriously it's only one of the strategies that we have found work with our setup. We don't have a robot with big forks on the side that grip your robot and pull it to our zone like some others I have seen. We don't have 10 motor tank drive either so we probably won't win pulling matches either against those types of robots. We do have an extremely fast robot with interlocked 4 wheel steering that has much drive time on it. How rough this game gets this year depends on the other teams. If everyone wants to be nice we will be very nice, but if people start doing full speed runs into robots (including ours) with the goal catchers and the refs don't cool it down, things WILL get ugly this year.

Before anyone gets bent out of shape (j/k) we know this isn't Battlebots and we need to be gracious but how do you graciously take a goal from someone? Without using force be it dragging their robot to a new zone or attempting to free it from their gripper?

Katie Reynolds
02-19-2002, 05:10 PM
Yea... here's ours...

93's grabber (http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=2182&direction=DESC&sort=date&perrow=4&trows=3)

- Katie

Matt Reiland
02-19-2002, 05:23 PM
That looks like a 'robust' design, nice.

Is it like ours where you drive straight in and when it gets past the bars its automatically sprung back and latched like it looks like it is?

Wetzel
02-19-2002, 05:43 PM
Originally posted by FIRSTAE2004
Yea... here's ours...

93's grabber (http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=2182&direction=DESC&sort=date&perrow=4&trows=3)

- Katie

Do I see floppys? :)

Chubtoad
02-26-2002, 11:11 AM
Team 271 Grabber (http://bshs.bayshore.k12.ny.us/robotics/images/grabber.jpg)

If you want to go to the Bay Shore site, there is a pic of the whole bot, we will be updating it soon, but with school I haven't gotten the chance to. Also soon a movie of the bot working.

Trust me on the fact that those grabbers are robust. and yes once they grab the goal they pull it into the bot.:D

aka Scott White
02-26-2002, 11:27 AM
Our gripper is very similiar to team 93's. Except for the pneumatic pushing it down to be level with the playing field, our arm functions with no assisstance from the rest of our robot, and as far as we can tell, as close to guaranteed to work as it is possible to be; its spring loaded, and cannot detach from the goal without manual asstance after the match.

Greg Needel
02-26-2002, 12:15 PM
as far as my team goes we definatly agree with kiss. so here is our simple grabber I'll post a better pic when I can find one

Wetzel
02-26-2002, 03:06 PM
Team 271, you may want to consider adding some shielding at your regional, if you havn't already. I'm looking that the speed controler in the lower left in particular.

Joe Johnson
02-26-2002, 03:29 PM
My biggest nightmare is the sideload issue.

Specifically, how much of a load can the gripper take before it plastically deforms your gripper (or the guide system which is just as bad and perhaps even worse)

We initially had a very basic structure. When we analized the loads, we discovered that it would deform plastically at about 200 pounds of side loading. We decided that this was too close to the edge. Afterall, we can put more than 200 pounds of force on the goal all by ourselves in a static load condition, a dynamic load case in the heat of battle will very likely exceed 200 lbs.

In the the end we compromised at 500 pounds designed side load (with a bit of a safety factor thrown in for good measure). It made our mechanism (and our guide system) a little more complex, but in then end, I think we will have a trouble free mechanism.

Every team will have to decide where the right balance between KISS and a robust & reliable mechanism.

Time will tell how well each teams has balanced the scales...


Joe J.

Chubtoad
02-26-2002, 07:41 PM
hmm, never thought about a robot coming in that way, the goal comes no where close to that, the reason it is so close to the edge is actually cause of weight;) we were lucky though, when we cut those sections out, (which if you look from the front as in the other pic on the website Looks like two "M"s which is Cool cause our initials are MM) it made the robot look a lot cooler!
Thanks for the idea though, i'll defintly see if we can add some protection there. We added a piece of corrogated lexan (think cardboard, but lexan instead) over where the balls would drop from our basket (if we weren't over a goal) to protect electronics, but I am going to try to convince them to make sure we move it to a casing over the whole main section

As far as side loads, we made reinforcement sections on our entire robot, to compensate for any directional force we could think of. So we hoping ::wink wink:: that it holds up. We are actually currently making a copy of the robot we shipped to test stuff out and practice with, we have the whole drive system done, which is good cause in practice today we sheared a pin, so we are making a list of things we have to change once we get to our first regional!

Anybody else have comments on 271's grabber?

Ragin_Kage
02-27-2002, 07:38 PM
I think my team will be notorius for our goal grabber designs...We've got a "Twist n' Lock" in the front and two "Battle Axes" on the sides.... http://middlesexboro.net/powercord/pictures/146.JPG

there are more pics on our website

we are rookies, so watch out for us in NJ and St. Louis regs.

Ragin_Kage
02-27-2002, 07:39 PM
that picture is quite old, so dont worry about all our wires being exposed, we got it all under control, haha

Jeremy_Mc
02-28-2002, 12:28 AM
As well designed as all these grabbers are, we went through most of these concepts during our design phase(s). :) But we ultimately came up with a design that would allow us to "hug" the goal, contact it on three sides, grab it on two. Then lift up and transfer the weight of the goal in its entirity to the chassis and drive system of our robot, thus giving us MAJOR torque, traction, and frankly power. :) Also it gives up complete control of that particular goal. We added a second goal grabber that is very simple, but with the amount of torque that the goal's weight allows us, we don't need anything else fancy. ;)

Mike Norton
03-01-2002, 04:36 PM
this is the one grabber that can grab goals or robots :D
http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=2178&direction=DESC&sort=date&perrow=4&trows=3

this one will grab a goal and not let go;)
http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=2179&direction=DESC&sort=date&perrow=4&trows=3

this is the same grabber on the robot

http://www.valleytech.k12.ma.us/Robotics/images/2002%20Claw.jpg

We used a nice cable that will let the goal do 360 around the robot. this way we can always pull.

the first grabber let us turn 90 each way. this design has been proven out in the past to be very sturdy.


I say let the jousting begin

Matt Reiland
03-01-2002, 04:51 PM
Mike,

Looks like your motor mount may have slipped a little from the 1st picture, the sprockets don't seem aligned.

Mike Norton
03-01-2002, 04:59 PM
The big sprocket you see is warped we welded a square stock to the inside of it. we used this only to test it out. We have another one that does line up nice.


48 or a 24 tooth that will be what we will be thinking of.



48 is fast and powerful, powerful enough to move the goal as it comes out.

24 is slower but much much stronger this can crush thing. Only use will be if things get rough.